Organolithium reagents are organometallic compounds that contain carbon–lithium bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.
Cerium(III) chloride (CeCl3), also known as cerous chloride or cerium trichloride, is a compound of cerium and chlorine. It is a white hygroscopic salt; it rapidly absorbs water on exposure to moist air to form a hydrate, which appears to be of variable composition, though the heptahydrate CeCl3·7H2O is known. It is highly soluble in water, and (when anhydrous) it is soluble in ethanol and acetone.
Organoborane or organoboron compounds are chemical compounds of boron and carbon that are organic derivatives of BH3, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds.
Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula [(CH3)2N]3PO. This colorless liquid is a useful reagent in organic synthesis.
The Danishefsky Taxol total synthesis in organic chemistry is an important third Taxol synthesis published by the group of Samuel Danishefsky in 1996 two years after the first two efforts described in the Holton Taxol total synthesis and the Nicolaou Taxol total synthesis. Combined they provide a good insight in the application of organic chemistry in total synthesis.
Acyloins or α-hydroxy ketones are a class of organic compounds which all possess a hydroxy group adjacent to a ketone group. The name acyloin is derived from the fact that they are formally derived from reductive coupling of carboxylic acyl groups.
Ruthenium tetroxide is the inorganic compound with the formula RuO4. It is a yellow volatile solid that melts near room temperature. It has the odour of ozone. Samples are typically black due to impurities. The analogous OsO4 is more widely used and better known. One of the few solvents in which RuO4 forms stable solutions is CCl4.
The Rubottom oxidation is a useful, high-yielding chemical reaction between silyl enol ethers and peroxyacids to give the corresponding α-hydroxy carbonyl product. The mechanism of the reaction was proposed in its original disclosure by A.G. Brook with further evidence later supplied by George M. Rubottom. After a Prilezhaev-type oxidation of the silyl enol ether with the peroxyacid to form the siloxy oxirane intermediate, acid-catalyzed ring-opening yields an oxocarbenium ion. This intermediate then participates in a 1,4-silyl migration to give an α-siloxy carbonyl derivative that can be readily converted to the α-hydroxy carbonyl compound in the presence of acid, base, or a fluoride source.
In organic chemistry, the Baudisch reaction is a process for the synthesis of nitrosophenols using metal ions. Although the products are of limited value, the reaction is of historical interest as an example of metal-promoted functionalization of aromatic substrates.
The Kuwajima Taxol total synthesis by the group of Isao Kuwajima of the Tokyo Institute of Technology is one of several efforts in taxol total synthesis published in the 1990s. The total synthesis of Taxol is considered a landmark in organic synthesis.
Barry M. Trost is an American chemist who is the Job and Gertrud Tamaki Professor Emeritus in the School of Humanities and Sciences at Stanford University. The Tsuji-Trost reaction and the Trost ligand are named after him. He is prominent for advancing the concept of atom economy.
Selenoxide elimination is a method for the chemical synthesis of alkenes from selenoxides. It is most commonly used to synthesize α,β-unsaturated carbonyl compounds from the corresponding saturated analogues. It is mechanistically related to the Cope reaction.
The Achmatowicz reaction, also known as the Achmatowicz rearrangement, is an organic synthesis in which a furan is converted to a dihydropyran. In the original publication by the Polish Chemist Osman Achmatowicz Jr. in 1971 furfuryl alcohol is reacted with bromine in methanol to 2,5-dimethoxy-2,5-dihydrofuran which rearranges to the dihydropyran with dilute sulfuric acid. Additional reaction steps, alcohol protection with methyl orthoformate and boron trifluoride) and then ketone reduction with sodium borohydride produce an intermediate from which many monosaccharides can be synthesised.
Pyridine-N-oxide is the heterocyclic compound with the formula C5H5NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peroxyacids as the oxidising agent. The molecule is planar. The compound is used infrequently as an oxidizing reagent in organic synthesis. It also serves as a ligand in coordination chemistry.
Electrophilic amination is a chemical process involving the formation of a carbon–nitrogen bond through the reaction of a nucleophilic carbanion with an electrophilic source of nitrogen.
Oxidation with chromium(VI) complexes involves the conversion of alcohols to carbonyl compounds or more highly oxidized products through the action of molecular chromium(VI) oxides and salts. The principal reagents are Collins reagent, PDC, and PCC. These reagents represent improvements over inorganic chromium(VI) reagents such as Jones reagent.
Reductions with samarium(II) iodide involve the conversion of various classes of organic compounds into reduced products through the action of samarium(II) iodide, a mild one-electron reducing agent.
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligands stabilize high oxidation states of a metal. They are also found in several metalloproteins, for example in molybdenum cofactors and in many iron-containing enzymes. One of the earliest synthetic compounds to incorporate an oxo ligand is potassium ferrate (K2FeO4), which was likely prepared by Georg E. Stahl in 1702.
An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to amides and participate in [3+2] cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center.
In organic chemistry, the Davis oxidation or Davis' oxaziridine oxidation refers to oxidations involving the use of the Davis reagent or other similar oxaziridine reagents. This reaction mainly refers to the generation of α-hydroxy carbonyl compounds (acyloins) from ketones or esters. The reaction is carried out in a basic environment to generate the corresponding enolate from the ketone or ester. This reaction has been shown to work for amides.
